How is tax calculated in SeedCode Complete?
Tax begins in the Items table (select Settings from the layout menu, the click on the Items tab) where items are either marked taxable or not.
This taxable attribute is looked up into the InvoiceLines table when an item is added to an invoice. Since this value is looked up you can change the taxable status of an item once it is on the invoice; you can also add a tax status to invoice lines that might not be related to an item (ad hoc lines).
The taxable amount of an invoice line is also calculated in the InvoiceLines table: in the field "PriceLineTotalTaxableAmountCalc".
The taxable amount of the invoice is determined in the script "Calculate Invoice Total"; and the tax itself in the field Invoices::TaxCalc; that field looks to see if the invoice itself is taxable (the customer may be tax exempt) and what the tax rate is (the tax rate is stored in Invoices::TaxRate).
That tax rate is set into the invoice in the script "New Invoice" which contains the default tax rate. If you need to change your tax rate by customer location, you'll need to add a separate set field for the tax rate into the end of the scripts "Select Contact for Invoice" and "Select Company for Invoice".